asm/dma-mapping-common: Clarify output of dma_map_sg_attrs

[sfrench/cifs-2.6.git] / include / asm-generic / dma-mapping-common.h

diff --git a/include/asm-generic/dma-mapping-common.h b/include/asm-generic/dma-mapping-common.h
index 3378dcf4c31ea85b7206fe8b5e03be828330c56d..940d5ec122c96e5a72173b9db2d0bcff44d39405 100644 (file)
--- a/include/asm-generic/dma-mapping-common.h
+++ b/include/asm-generic/dma-mapping-common.h
@@ -39,6 +39,10 @@ static inline void dma_unmap_single_attrs(struct device *dev, dma_addr_t addr,
        debug_dma_unmap_page(dev, addr, size, dir, true);
 }
 
+/*
+ * dma_maps_sg_attrs returns 0 on error and > 0 on success.
+ * It should never return a value < 0.
+ */
 static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
                                   int nents, enum dma_data_direction dir,
                                   struct dma_attrs *attrs)
@@ -51,6 +55,7 @@ static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
                kmemcheck_mark_initialized(sg_virt(s), s->length);
        BUG_ON(!valid_dma_direction(dir));
        ents = ops->map_sg(dev, sg, nents, dir, attrs);
+       BUG_ON(ents < 0);
        debug_dma_map_sg(dev, sg, nents, ents, dir);
 
        return ents;